By carrying on family tradition, Sara Vivenzio also reinvented her career.

Sara Vivenzio can tell how old an aged Cheddar is just by looking at it. The head of the Cheese School of San Francisco (where classes include "The Remarkably Redolent and Ravishing World of Robiola" and "Sugar Loves Mold: Dessert Wine and Cheese"), she seems to be a mystic of the dairy arts. But just five years before she founded the nation's only independent institution devoted to cheese appreciation, Vivenzio was an award-winning Manhattan advertising executive.

"I designed direct-mail campaigns, which are probably the least sexy thing about the advertising world," says Vivenzio, whose clients included Mercedes-Benz and Pitney Bowes. When her boyfriend (now husband) got a job in San Francisco and asked Vivenzio to join him there, she surprised herself by saying yes—but wondered what her next career move might be. On the cross-country drive, whizzing by countless farms and grazing cows, Vivenzio found herself daydreaming about cheese: Her great-grandparents were cheesemakers in their native Italy, and her grandparents prepared fresh mozzarella and ricotta for their grocery in upstate New York. Plus, Vivenzio had read about a groundswell of artisanal-cheese purveyors in the Bay Area. "I landed in our new city with cheese dancing around in my head," she said. "It seemed romantic."

Her first step was anything but: a $10-an-hour gig at a cheese shop. Learning quickly on the job, she was the store's primary buyer within a year and started organizing cheese education classes in a cramped back storeroom, to ever-increasing demand. With the shop owner's blessing, Vivenzio opened the Cheese School of San Francisco across the street, later moving to a historic 1907 brick building in the North Beach neighborhood.

Pregnant with her second child, Vivenzio is pulling longer hours than ever as her school's curriculum grows. But she never misses her Madison Avenue days. "Now a business trip is to wine country or a food festival," she says. "I love it all. You can't serve ad copy at a dinner party, but a beautiful cheese tray is always a big hit."